Timber Linear Elements Properties - EC 5

 

In Advance Design, the calculation of timber linear elements typically follows global timber design assumptions based on the current standards. For more precise control and customization, you have the option to define local timber assumptions for each element.

 

 

Accessing the Timber Design Properties of the selected element

This customization is accessible through the properties window, where you can select Timber Properties from the Properties filter dropdown to focus exclusively on the timber design properties of your selected element(s).

 

Properties window

 

 

Using the Properties window 

In the properties window, you can view and modify the properties of timber linear elements, allowing for detailed customization and management.

 

Key Features and Functions:

1. Clipping of forces

• Clipping: enables the clipping of forces option.
• Extremity: defines the clipping distance for the element extremities. The distance can be automatically calculated by the program or manually defined by the user.
• XY plane: defines if the clipping distance in XY plane is automatically calculated or user-defined.
• Value: displays the automatic clipping value for the XY plane. If the user-defined option is enabled, a custom value can be entered.
• XZ plane: defines if the clipping distance in XZ plane is automatically calculated or user-defined.
• Value: displays the automatic clipping value for the XZ plane. If the user-defined option is enabled, a custom value can be entered.

 

1. Timber Design

• To calculate: when this option is enabled, the element is taken into account at the timber calculation. When disabled, the concerned elements are not calculated.
• Design results: Displays whether timber design results are available for this element.
• Work Ratio: Displaying maximum working Ratio value of all design verifications executed inside Advance Design for this element.
• General Design Template: You can assign a design template that defines the element design properties. Select one of the available templates from the drop-down list.
• Service class: Defines the service class for the element which is taken into account at the timber calculation. Service class is determined according to environmental conditions.
• Humidity percentage: Defines the humidity percentage of the surrounding air.
• Systems effect coefficient Ksys: The member strength properties can be multiplied by a group effect factor (ksys), when several elements with the same function are laterally connected by a continuous load distribution system.

 

1. Spaced Columns

• Length of unrestrained bays (midlines) L1: Distance between axes of two consecutive connectors.
• Connectors: Type of connectors used for spaced columns (Nailed packs, Glued packs, Bolted packs, Glued gussets, Nailed gussets).

 

1. Fire design

• Fire exposure time: time (in minutes) of fire exposure
• Delay of burning: delay of burning due to protection (in minutes)
• Resistance of planking (min): resistance of planking (in minutes)
• k2: insulation coefficient [m/min]
• k3: post-protection coefficient [m/min]
• Exposed faces: displays the Fire design dialog box, where the user can specify which element faces are exposed to fire. For each side of the cross section it is possible to enable the fire exposure.

 

Fire Design

 

1. Deflections

• Elem. verification: Enables / disables the deflection verification of the element.
• Deflections: Defines the constructive and the allowable deflections.

• Constructive defl. Wc: constructive deflection (if applied)
• Allowable defl. Winst: instantaneous deflection due to Q loads only
• Allowable defl. Wnet,fin: effective final deflection
• Allowable defl. Wfin: final deflection without considering Wc
• Verif. location: select from the drop-down list the location on the element for which the deflection are verified (extremity, span, envelope).

• Super Elem. Verification: Take into account the super element at deflection verification.
• Super elem. Deflections:

• Constructive defl. Wc: constructive deflection (if applied)
• Allowable defl. Winst: instantaneous deflection due to Q loads only
• Allowable defl. Wnet,fin: effective final deflection
• Allowable defl. Wfin: final deflection without considering Wc
• Verif. location: select from the drop-down list the location on the element for which the deflection are verified (extremity, span, envelope).

 

For code EN 1995-1-1 (French NA) an additional verification can be enabled: Wtot2, the deformation sustained by the floor finishes (fragile elements). By default, this verification is disabled.

 

Deflection Design, additional check for

code EN 1995-1-1 (French NA)

 

 

• Share of floor finishes (G2/G): This represents the amount of permanent loads corresponding to the floor finishes (G2), as a ratio over the total permanent load (G).  
   

The amount of permanent loads anterior to the floor finishes (Ginst) is the difference between the total permanent loads and the permanent loads corresponding to the floor finishes (G2).

Wtot2=Wfin-Winst, G

Where Wfin is the deflection at the SLS Characterisitc (i.e. G+Q).

 

If several permanent cases are present, a combination must be created where all the permanent actions are grouped. This grouping occurs automatically with the detailed combinations but needs to be manually configured with simplified combinations.
 

 

1. Buckling

• Elem. verification: Enables / disables the buckling verification of the element.
• Buckling length: allows the definition of buckling lengths for the selected element. In the corresponding cell, click to access the Buckling configuration dialog box.
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Buckling dialog

 

 

• Shape subject to buckling: specifies if the element is subject to buckling or not. If not, the reduction factors (i.e., min, ky and kz) are not calculated and are considered equal to 1.

• xz plane - large inertia and xy plane - small inertia: define the calculation mode of the buckling lengths for the xy and xz plane of the selected timber element.

  • L0: length of the element to the next point of support in the plane buckling.

  • Lfz, Lfy: buckling length about the local y and z axes, associated to the Iz / Iy inertia.

    • Auto calculation: calculates the buckling using the method specified in the Timber design settings dialog box.

    • Imposed value: calculates the buckling lengths by a value entered in the corresponding field.

    • Super-element ratio: calculates the buckling lengths by a specified value multiplied by the super-element length.

    • Element ratio: calculates the buckling lengths by a specified value multiplied by the element length.

    • Mesh size ratio: calculates the buckling lengths by a specified value multiplied by the mesh size.

  • Lfz fire and Lfy fire: define the buckling length for fire verification about z and y local axes.

  • = Lf: the buckling length for fire verification is equal to the buckling length (Lfz or Lfy).

    • Imposed value: calculates the buckling lengths for fire verification by a value entered in the corresponding field.

    • Super-element ratio: calculates the buckling lengths for fire verification by a specified value multiplied by the super-element length.

    • Mesh size ratio: calculates the buckling lengths for fire verification by a specified value multiplied by the mesh length.

    • Fixed Lf: calculates the buckling lengths for fire verification by a specified value multiplied by the buckling length (Lfz or Lfy).

 

The blue highlighted fields display the calculated buckling lengths, Lfz and Lfy, when the timber calculation is completed.

 

 

1. Lateral-torsional Buckling

• Elem. verification: when enabled, the element will be taken into account at buckling verification.

• Lateral-torsional Buckling: click to access the Lateral-torsional buckling dialog box, where you can configure the lateral-torsional buckling length calculation.

 

 

1. Notches

Two nodes are having the same properties – the first is Start Notch and the second is End Notch.

1. Start Notch: Configuration of the verification of the stress concentration at the notch at the start of the beam.
2. End Notch: Configuration of the verification of the stress concentration at the notch at the end of the beam.

• Notch location: Location of the notch. This combo list contains 3 options: None, On the same side as the support, or On the opposite side of the support.
• Beam start height (hef): The effective depth of the beam on the support.
• Support to notch distance (x): The distance x from the line of action of the support reaction to the corner of the notch.
• Inclined part length (Li): The length of the inclined part.

 

 

1. Bearing at supports

Two nodes are having the same properties – for the start and the end of the element.

1. Start support: Configuration of the verification of the bearing at the support at the start of the beam.
2. End support: Configuration of the verification of the bearing at the support at the end of the beam.

• Verification: Verification of bearing on the support located at the start /end of the element.
• Support width (L): The contact length on the support.
• Beam edge to support edge distance (a): The distance from the end of the beam to the face of the support.

 

By using local timber assumptions, engineers can ensure that each element's design is optimized for its specific role within the structure, improving both performance and compliance.

 

 

Related Topics

• Linear Elements

• Timber Calculation